Betfair have issued another apology to customers over the voided bets on Voler La Vedette at Leopardstown. Photograph: Anna Gowthorpe/PA

Betfair have made another apology to punters over the bizarre betting patterns in Wednesday's Christmas Hurdle at Leopardstown and the delay in settling the outcome.

The betting exchange eventually voided all in-running bets in the race, in which one client was left with a liability of nearly £23m on the easy winner Voler La Vedette.

It became evident during the race that over £21m was available at odds of 28-1 to back Voler La Vedette, even though Colm Murphy's mare went off at 13-8 on course, and some eagle-eyed backers thought they had picked up a late Christmas present.

However, Betfair voided the race due to a "technical fault" which they said had caused a customer to exceed their exposure limit.

A Betfair statement on Thursday said: "Firstly, we would like to reiterate that anyone betting in-running in yesterday's Leopardstown race clearly received a very poor customer service and betting experience. We apologise once again for this.

"We have identified the issue and replicated it in a test environment last night. A fix was applied overnight, and is now subject to rigorous testing.

"Contrary to some media speculation, we can confirm that all in-running bets on this market would have been voided, had Voler La Vedette won or lost. There was never any chance of the account in question profiting yesterday. The account in question was also immediately suspended after the Leopardstown race.

"There has been some criticism from customers, and in the press, that Betfair took too long to void.

"Quite simply, we made the decision after we were in full possession of the all the facts and input from the relevant internal departments. A decision was then made to void in accordance with our terms and conditions."